Japanese disclosure Gazette 1983-37179 discloses a technique for forming a sheet of film into a package f.sub.5, as shown in FIG. 8, comprising a tube of rectangular cross-section. Such construction is disadvantageous in that a rear sealing line f.sub.5 of double thickness extends along a longitudinal center line of one side and often spoils or detracts from the external appearance causing difficulties in printing. Furthermore, the package is susceptible to deformation when filled with a product and is of inherently poor durability, because the four corners are defined merely by respective folds.
Another well known form of package, shown in FIG. 9, represents an improvement in that the rear sealing line extends along one corner and the remaining three corners are formed with rib-like projections for sealing, obviating the above mentioned disadvantages and resulting in a package of both improved strength and appearance.
However, the packages shown in both FIGS. 8 and 9 were specifically designed to be filled with liquids and it is difficult for such packages to be effectively utilized for packing non-flowable materials such as resiliently deformable articles.
In view of difficulties experienced in attempting to package resiliently deformable articles into a box-shape by using soft film, a conventional approach has been to package the articles as a sheet folded into a square tube i.e., in so-called pillow packaging fashion, or to provide rib-like projections along respective corners of the square tube during formation thereof by the sheet and then to seal such rib-like projections to obtain the box-shape package. However, it is, nevertheless, difficult to package a bunch or stack of soft, resiliently compressible articles such as paper diapers or sanitary napkins into a neat box-shape using such approach.